SIRT5 stabilizes mitochondrial glutaminase and supports breast cancer tumorigenesis.

Greene, Kai Su; Lukey, Michael J; Wang, Xueying; Blank, Bryant; Druso, Joseph E; Lin, Miao-Chong J; Stalnecker, Clint A; Zhang, Chengliang et al. · Proc Natl Acad Sci U S A · 2019

basic_science · Level V

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Abstract

The mitochondrial enzyme glutaminase (GLS) is frequently up-regulated during tumorigenesis and is being evaluated as a target for cancer therapy. GLS catalyzes the hydrolysis of glutamine to glutamate, which then supplies diverse metabolic pathways with carbon and/or nitrogen. Here, we report that SIRT5, a mitochondrial NAD<sup>+</sup>-dependent lysine deacylase, plays a key role in stabilizing GLS. In transformed cells, SIRT5 regulates glutamine metabolism by desuccinylating GLS and thereby protecting it from ubiquitin-mediated degradation. Moreover, we show that SIRT5 is up-regulated during cellular transformation and supports proliferation and tumorigenesis. Elevated SIRT5 expression in human breast tumors correlates with poor patient prognosis. These findings reveal a mechanism for increasing GLS expression in cancer cells and establish a role for SIRT5 in metabolic reprogramming and mammary tumorigenesis.